The National Institute for Occupational Safety and Health (NIOSH) in partnership with Strata Products tested the sealing capability of Ventstop®™ as part of an ongoing mine fire control and suppression research program. Ventstop®™ is a multi-purpose, inflatable device that is produced by Minvent Solutions (now M2P Engineering) and is available worldwide for use in the metal and nonmetal mining industry. Ventstop®™ is also used in the Australian coal industry as a temporary ventilation control device. The device can be quickly deployed, is reusable and can be placed in horizontal and vertical mine voids to control dust, fumes and smoke. Deployment, multi-day inflation and air leakage tests were conducted at the NIOSH Lake Lynn Laboratory to determine the capability and limitations of Ventstop®™ in a simulated coal mine setting. During the tests, Ventstop®™ was also subjected to low-level forces of a nearby methane gas ignition. It is thought that Ventstop®™ could be used by the US coal mining industry to temporarily close an underground mine area in response to a fire or spontaneous combustion heating event, to temporarily redirect mine ventilation during longwall equipment moves or during stopping construction. This paper describes this inflatable temporary mine sealing technology and presents the results of the NIOSH tests.